Turkish Internet servers have been hit by a powerful cyberattack, which has disrupted banks and public institutions.
Turkish banks reported on December 25 that credit card transactions faced sporadic disruption after hackers stepped up a two-week onslaught of cyberattacks.
The "tr" domain under attack is used by websites belonging to ministries, banks, and commercial enterprises.
The NGO that administers addresses for websites using this domain said that the attack appears to be from "organized sources" outside of Turkey.
Transport and Communications Minister Binali Yildirim called it a "serious attack."
Local media have suggested that the attack could be coming from Russia, citing an ongoing bitter row between Moscow and Ankara following the latter's downing of a Russian warplane near the Syrian border in November.
Separately, the Anonymous hacking group announced that cyberattacks would continue if Turkey "doesn’t stop supporting Islamic State."